Burner end cone having two different types of vanes



May 14, 1968 w. 0. DYSART ET AL 3,383,052

BURNER END CONE HAVING TWO DIFFERENT TYPES OF VANES Filed June 28, 19662 Sheets-Sheet l May 14, 1968 w, DYSART ET AL 3,383,052

BURNER END CONE HAVING TWO DIFFERENT TYPES OF VANES Filed June 28, 19662 SheetsSheet INVENTOR. W/450A/ 0. firs/W7 W/AL/4M J 2044/4/65? ATTORNEYUnited States Patent 3,383,052 BURNER END CONE HAVING TWO DIFFERENTTYPES OF VANES Wilson D. Dysart and William J. Zollinger, Crystal Lake,

111., assignors to Union Oil Company of California, Los

Angeles, Calif., a corporation of California Filed June 28, 1966, Ser.No. 561,218 15 Claims. (Cl. 239-490) This invention relates to animproved burner for combusting hydrocarbon fuels, and more particularly,to an improved burner end cone which affords reduced restriction to airflow and higher maximum firing rates Without loss of combustionperformance.

'It is well known to those skilled in the combustion art that themechanical features of burners used in the combustion of hydrocarbonfuels are important factors in attaining smoke-free combustion atminimum excess air, the measure of a burners ability to effectsmoke-free combustion at minimum excess 'air being designated thecombustion performance. Accordingly, various burner designs have beenproposed for the combustion of these fuels. Although it has beenpossible to modify burner head assemblies to achieve high combustionperformance, it has not always been possible to construct a highlyeflicient apparatus which is mechanically simple in design, relativelylow cost, and able to perform at a reasonably low noise level. Oneburner assembly realizing these important criteria is proposed in ourcopending application Ser. No. 388,250, filed Aug. 7, 1964, now maturedinto US. Patent No. 3,361,365. This burner comprises 'a hollow conicalair shield disposed within a convergent end cone having angularlypitched vanes on its interior surface to impart rotational motion tofluids passing therethrough. Combustion air passes into the combustionzone through both the annular area between the air shield and the endcone and through the hollow air shield. Atomized fuel is ejected intothe air stream passing through the air shield. An additional portion ofair passes from the annular area into the interior of the 'air shieldthrough a plurality of triangular shaped slots in the air shield. Fluidguide means on the exterior surface of the air shield adjacent theseslots impart rotational motion to the air passing into the interior ofthe air shield through the slots similar to that imparted to the airpassing through the vaned annulus.

While the foregoing burner assembly, and other conventional burners ofthe choke type, wherein a substantial portion of the combustion airpasses through an annular area between an end cone and an air shield,are highly effective combustion devices; they are generally limited infiring rate because of reduced combustion air capacity. Further,although the vanes and other flow directing devices placed in the airpassages to produce turbulence and impart rotary motion to thecombustants are conducive of high combustion performance, theyconstitute additional restrictions to the flow of combustion air intothe combustion zone. Thus, for an equal size air tube, these highperformance burners have substantially reduced firing capacity becauseof the limited combustion air capacity. In new construction, thiscapacity restriction can usually 'be overcome at some additional expenseby the use of larger combustion air blowers, or by increasing the numberof burners installed. However, these changes have become extremelycostly where annular flow burners are installed in existing furnaces.Modification of the end cone vane and air shield construction to affordhigher air capacity has heretofore usually resulted in an undesirablereduction in combustion performance.

Accordingly, it is an object of the present invention to provide animproved burner having high combustion performance and reduced air flowrestriction. Another object is to provide an end cone of improved designfor use with an annular air flow burner. Still another object is toprovide a burner end cone having a high air capac ity which impartsrotative motion to fluids passing therethrough. These and other objectsof the present invention will become apparent to those skilled in theart from the following detailed description and by reference to theaccompanying drawings, of which:

FIGURE 1 is an end view of the burner end cone of the present inventionas seen from the fluid inlet end.

FIGURE 2 is a side view of the burner end cone in cross-section takenalong the line 2-2 of FIGURE 1.

FIGURE 3 is an elevation view partially in cross-section showing anannular flow burner assembly mounted in a horizontal position andemploying the end cone of this invention.

Briefly described, the present invention contemplates an improved burnerend cone for installation at the discharge end of a burner air tube. Theend cone comprises a short annular body member having a central fluidpassage extending its length communicating with an open fluid inlet atone end and a fluid outlet of reduced size at the opposite end. Theinterior surface of the end cone which defines the central fluid passageis preferably shaped to provide a smooth transition from the inletopening to the smaller diameter outlet opening and is provided with aplurality of curvilinear vanes or ribs protruding inwardly therefrom.These vanes are spaced about the inside perphery of the annular body andare oriented at an angle from the axis of the body. The pitch of thevanes is reduced near the inlet end of the cone so as to offer lessrestriction to fluid flow in this critical area. Alternate vanes extendthe length of the member from the inlet Opening to the outlet opening.Disposed between each of these vanes and generally at the same anglefrom the axis of the body are shorter vanes extending from a pointintermediate the length of the body to the outlet opening. Thesecurvilinear v'anes protruding from the interior surface of the annularbody impart rotational motion to the fluids passing through the end coneand discharging therefrom without excessively restricting the flow ofthese fluids. The end cone can be conveniently adapted to fit variousstandard size burner tubes.

Referring to FIGURES 1 and 2 in greater detail, the end cone comprisesannular body 10 of unitary structure which is generally symmetricalabout a central axis and which is adapted for mounting at the outlet endof a burner air tube in a manner to be subsequently more fullydescribed. Annular body 10 is of relatively short length and has openends to accommodate the passage of fluids through the center flow area.Fluids are received into the end cone through one open end of theannular structure, pass the length of the body, and are discharged atthe opposite outlet end. The outlet opening of the end cone is ofsmaller size than the inlet opening so as to afford a nozzle-like fluidpassage. Although the size of the center flow passage can be varied 'asnecessary to accommodate increased burner capacity, the various end conedimensions are preferably maintained within relative proportions toachieve optimum performance. Thus, although the fluid inlet opening canbe of any appropriate size, it is preferred that the cross-sectionalarea of the fluid outlet opening be maintained between about 50 and 65percent of the area of the inlet opening. For example, in a conventionaldomestic unit the end cone inlet can be a circular opening having adiameter of 3% inches which is equivalent to a cross-sectional area of10.32 square inches. Accordingly, the area of the outlet opening for aninlet of this size is preferably between about 5; 15 and 6.7 squareinches, Which corresponds to a circular opening having a diameterbetween about 2.56 and 2.93 inches. One especially preferred burner conehas an inlet opening 3% inches in diameter (10.32 square inches flowarea) and an outlet opening 2% inches in diameter (5.93 square inches inflow area).

In the illustrated device perferred in many applications, a shortsection 12 of body 10 adjacent the inlet is substantially in the form ofa right cylinder of constant inside diameter. The cylinder is thenuniformly reduced in inside diameter in adjacent section 14 to provide asmooth transition from the larger diameter of section 12 to the smallerdiameter of the outlet opening. Transition section 14 is preferablyformed by inturning the cylinder wall in the transition zone through acurvature of radius R Radius of curvature R is desirably maintainedbetween about 40 and about 60 percent of the radius of the cylinderinlet opening. Thus, the radius of curvature of transition section 14 ofthe aforementioned 3% inch end cone is preferably between about 0.73 and1.09 inches. Optimum performance can usually be obtained in a cone ofthis size if radius R is between about /8 and 1 inch. The overall lengthof the cone, as determined by the distance between the transverse inletand outlet faces at either end of annular body 10, is preferably lessthan about 50 percent of the diameter of the inlet opening and greaterthan about 30 percent of this dimension. An overall cone length of 1inches has been found satisfactory with the previously mentioned 3% inchend cone.

Rotary motion is supplied to the fluid passing through annular body 10by a plurality of curvilinear vanes on the interior surface of the conewhich can be conveniently formed integrally with the body structure, oralternatively, permanently affixed thereto as by welding, brazing, orthe like. These vanes comprise elongated protrusions extending from theinterior surface of the body wall into the fluid flow passage. The vanesare spaced about the inside periphery of the end cone and orientedthereon at an angle from the axis of the body so as to provide a desireddegree of rotary motion to the fluids discharged from the end cone. Theangle of the vanes from a line parallel with the axis of the annularbody largely determines the magnitude of the rotary motion imparted tothe fluids. This angle of inclination, or pitch, is illustrated by theangle Alternate vanes 16 extend the length of body 10, commencing at theinlet opening at one end of the body, and terminating at the outletopening at the opposite end thereof. Vanes 16 are smoothly curved towardthe inlet into a configuration more parallel with the axis of the bodyand with the direction of flow of the fluids entering the end cone. Thiscurvature is typically illustrated by the radius R which is preferablyalso between about 40 and 60 percent of the radius of the inlet opening.In an end cone of the size for use in a small burner for the usualdomestic furnace, radius R is typically between about inch and about 1%inches, the preferred radius of curvatures depending on the diameter ofthe inlet opening.

Interspaced between alternate full vanes 16 are partial vanes 18 whichcommence at an intermediate point on the interior surface of the endcone wall and extend to the outlet opening. Partial vanes 18 areinclined at the same angle 0 as full vanes 16. It is preferred thatpartial vanes 18 are tapered, such as at 20, to avoid a sharp protrusionprojecting upwardly into the fiow area. Thus, the height of vane 18gradually increases over the length of section 20 to a maximumequivalent to the height of vanes 16.

In a preferred modification of this invention, flow directing vanes 16and 18 have a constant pitch, or angle of inclination 9 over asubstantial portion of their length of between about 45 degrees andabout 75 degrees from a line parallel with the axis of the annular body.For most applications, the optimum angle of inclination 6 for thisconstant pitch section is about 60 degrees. As previously disclosed, theangle of inclination of vanes 16 is gradually 4 reduced adjacent theinlet opening so as to afford these vanes a more nearly axialorientation at the fluid inlet.

The angle of inclination is preferably reduced to an angle 9 of lessthan about 35 degrees. Satisfactory operation is usually obtainable atangles 0 of about 25 degrees, although even smaller angles are sometimespreferred. Vanes can be pitched for either clockwise or counterclockwiserotation, clockwise rotation being usually preferred.

Flow directing vanes 16 and 18 are generally of rectangularcross-section and project outwardly from the interior surface of annularbody 10. In a preferred embodiment, the radial projection of vanes 16and 18 into the flow area is limited so as to provide an unrestrictedcentral flow area through body 1%) of a diameter approximately equal tothe diameter of the fluid outlet opening. In a further preferredembodiment, vanes 16 and 18 project radially outwardly from the interiorwall of body 10 a variable distance to an imaginary right cylinderformed by the projection of the outlet opening the length of body 10coaxially therewith. Thus, the height of vanes 16 and 18, excepting fortapered section 20 of vanes 18, extend outwardly a variable distancefrom the interior wall of transition section 14, and a substantiallyconstant distance from the interior wall in cylindrical section 12.

Superior flow characteristics are obtained with vanes having a sharpradial projection outwardly from the interior surface of body 10 withoutfillets or rounded corners at the base of the vane.

Although the end cone of this invention can have any number of flowdirecting vanes on its interior surface, as necessary to impart thedesired degree of rotational motion to the fluids exiting therefrom,superior results are obtained with a device having between about fourand twelve vanes. The preferred device illustrated in FIG- URES 1 and 2is provided with four full vanes 16 uniformly spaced about thecircumference of the cylindrical end cone at degree intervals, and withfour partial vanes 18 uniformly spaced thereabout at 90 degree intervalsoffset 45 degrees from flow directing vanes 16. Because of the pitch ofthese vanes, their position about the periphery of body 10 will varydepending on the axial displacement, however, the vanes are maintainedin the same relative position throughout the length of the annularmember. Thus, at any transverse section of the illustrated preferreddevice, vanes 16 will be spaced 90 degrees about the interior surface ofthe cone and vanes 18 will be spaced 90 degrees apart offset 45 degreesfrom vanes 16.

The external configuration of body 10 can be adapted to the particularair tube with which it is to be employed. Since many domestic heatingfurnaces are constructed with either standard 378 inch or 4 inch I.D.air tubes, it is often preferred to construct the end cone so that itcan be conveniently adapted to either of these dimensions. A preferredembodiment of end cone adaptable to various different size air tubes canbe constructed by increasin the outside diameter of the cylinder insteps. In the illustrated device, body 10 is constructed with twodifferent outside dimensions to mate with two different size air tubes.Section 22 is constructed with a reduced diameter which is increased atsection 24. Both surfaces 22 and 24 can be tapered toward the inlet endto provide draft for casting. When the burner cone is installed on theair tube, radial face 26 or 28 will mate with the end of the air tube,depending on the size of the particular air tube. Tip surface 30 of body10 can be beveled an amount indicated by angle 0 as illustrated, tofacilitate casting, utility, appearance, and caulking at the furnacewall on installation. Bevel angle 0 can have a value of between about 25and about 45 degrees, and preferably is about 33 degrees.

The end cone of this invention can be conveniently fabricated fromvarious metals or metal alloys by casting the device in the desiredshape, or by boring and milling the vaned end cone from a solid block ofmetal by conventional metal working techniques. In an alternative methodof fabrication, a rough casting can be made having the general shape ofthe end cone, which is then finished by machining to final dimensions.

The installation of the end cone of this invention in an annular flowburner head assembly, such as that disclosed in our aforementioned U. S.Patent No. 3,361,365, is illustrated in FIGURE 3. The burner headassembly is installed in a suitable aperture 102 in combustion chamberwall 100, with the outlet of the assembly directed toward the interiorof the combustion chamber. The burner head assembly does not extend anyappreciable distance into the combustion chamber, the outlet face of theend cone preferably being installed flush with the inside surface ofwall 100. The burner head assembly comprises air tube 104 having securedto the end thereof an end cone substantially in accordance with thedevice illustrated in FIG- URES 1 and 2.

Disposed inside annular body of the end cone is hollow air shield 106having a truncated conical configuration or being cup-like in appearancewith the largest diameter of the air shield being substantially equal tothe diameter of the end cone outlet. Air shield 106 is slidably disposedwithin the end cone with the larger end thereof entering through thelarger end of the end cone and movable toward the smaller end thereof.Air shield 106 has a number of equally spaced triangular-shaped slots108 in the conical wall thereof communicating the exterior of air shield106 to the interior thereof. The slots or apertures 108 are tangentialto the smallest diameter of air shield 106 and have shapes similar toright spherical triangles. The greatest width of the slots is adjacentthe smallest diameter of air shield 106. These slots extend asubstantial distance toward the largest or flared end of the air shieldand are of such size so as to permit a sufficient amount of combustionsupporting fluid and fuel to be passed therethrough into the interior ofthe air shield for effective combustion. The tapered slots 108 have amaximum width of approximately inch to inch and taper to a point nearthe flared end of the air shield. The length of the slot may be of anysize, i.e., coextensive with the length of air shield 106, and islimited only by air shield structural considerations. That is if eitherthe tapered end or widest end of the tapered slot is too near thelargest or smallest end of the air shield respectively, flexibility andstructural weakness will result in the air shield. The size of slots 108should preferably allow between about 4 percent and 30 percent of theamount of air needed for combustion to flow therethrough.

Juxtaposed to slots 108 are fiuid guide means 110 projecting outwardlyfrom the exterior surface of the air shield. Guide means or fins 110have a spiral shape or louver configuration substantially correspondingto the contour of the exterior surface of the air shield so that fluidspassing over the exterior surface of air shield 106 will be partiallydiverted through slots 108 and enter the interior of the air shield witha rotary motion, the rotation of these fluids being substantially thesame as the rotational movement given the air passing through theannulus. The fin or guide means are coextending in length with the slotsand have a projection height of about A to /s inch with a preferredheight of about inch for the normal domestic burner. Ordinarily, theprojection height will generally approach the same dimension as thegreatest width of slot 108. Air shield 106 is fashioned of a relativelythin corrosion resistant metal such as stainless steel of about 14 to 28gage and has a substantially smooth interior and exterior surface exceptfor projecting fins or guides 110. While the slots may be punched out ofthe air shield and separately spirally shaped fins or air guide meanssecured adjacent the slot on the exterior surface of the air shield, itis preferred to make two cuts in the air shield with the subsequentbending out of that portion of the conical wall congruent with the slotto form the louver design.

It is preferred to space the slots at intervals of about 60 degreesaround the periphery of the shield, but smaller or greater spacings canbe used. One end of support means 114, preferably formed of bent metalrods is secured to the exterior surface of the air shield as by spotwelding or silver brazing. The other end of supporting members 114 aresecured to coupling 116 adapted to be slidably disposed on nozzleadapter 118 or fuel pipe 120. The supporting members 114 may be of anyshape so long as they are fashioned to provide ample clearance forignition electrode 122 and atomizing nozzle 124. Sufficient clearancebetween nozzle 124 and nozzle adapter 118 is provided so that coupling116 is movable axially thereof thereby allowing air shield 106 to befreely slideable within end cone 10. Coupling 116, after setting, isheld in fixed position at any predetermined position by means of setscrew 126. Alternatively, and preferably, the distance between the backend of the air shield and the nozzle orifice is fixed and placement ofthe air shield within the annulus is accomplished by moving the nozzle,nozzle adapter, and air shield as a unitary structure therebymaintaining a pre selected fixed distance between the nozzle orifice andthe air shield. This distance is set to obtain satisfactory flamepatterns and performance. Although a preferred method of mounting theair shield has been illustrated, the air shield may be supported withinend cone 10 by other means, as by supporting means secured to the airtube, nozzle, oil supply conduit, end cone, etc.

Packing or caulking material 128 and 130 is provided around end cone 10and air tube 104, respectively, at the combustion chamber wall so thatatmospheric air will not be drawn into combustion zone 132.

In operation, air is forced through air tube 104, by means not shown,toward the combustion chamber. Depending upon the position of air shield106 within annular body 10, a portion of the air necessary forcombustion passes through the annular flow area between body 10 and airshield 106 and is introduced into combustion zone 132 in turbulentfashion, rotational movement being given the air by vanes 16 and 18.Another portion of the combustion air will impinge upon the exteriorsurface of air shield 106 and will be diverted by fins through slots 108into the interior in similar rotational manner as the air passingthrough the annulus. Another portion of air will be admitted through theopen back of air shield 28 along with atomized fuel delivered underpressure through fuel pipe and atomizing nozzle 124.

The end cone of the present invention, in combination with an annularburner of the type disclosed in our aforementioned U.S. Patent No.3,361,365, results in a substantially increased combustion air capacityand a corresponding increase in firing rate. Air flow and firing ratescan be increased as much as 50 percent, or more, without loss ofcombustion performance. For example, a burner assembly of the previousdisclosed type having a 3% inch inlet and eight 60 degree full lengthvanes was tested at a maximum air flow of 163.5 lb./hr. and a maximumoil firing rate of 1.41 gallon per hour at 11.0 percent excess air at #2smoke. Excess air is defined as that air in excess of the amounttheoretically required to completely burn the fuel. The same burnerhaving a 3% inch end cone with four full length 60 degree pitch vanescurved to 25 degrees at the inlet and four partial vanes interspacedtherebetween, in accordance with the preferred device illustrated inFIG- URES 1 and 2, exhibited a maximum air flow of 232.0 lb./ hr. and amaximum firing rate of 2.0 gallons per hour at 11.0 percent excess airat #2 smoke.

While particular embodiments of the invention have been described, itwill be understood, of course, that the invention is not limited theretosince many modifications can be made, and it is intended to includewithin the invention any such modification as fall within the scope ofthe claims.

The invention having thus been described, we claim:

1. A burner end cone comprising an annular body member having a fluidinlet opening at one end, a fluid outlet opening of reduced size at theopposite end, and an internal flow passage extending the length of saidbody member communicating said inlet with said outlet: a plurality offirst flow directing vanes protruding from the interior surface of saidbody member into said flow passage and extending the length of said bodymember from said inlet opening to said outlet opening, said vanes beingangularly displaced from a line parallel with the center axis of saidbody member; and a plurality of second flow directing partial vanesprotruding from the interior surface of said body member, said secondvanes being alternately disposed between said first vanes and extendingfrom a point on the interior surface of said body member intermediatesaid ends to said fluid outlet.

2. The article defined in claim 1 wherein said annular body membercomprises a hollow right cylinder having an inturned section ofcontinuously decreasing inside diameter adjacent said outlet openingwhich defines an interior surface affording a smooth transition from theinside diameter of the right cylinder to that of said outlet opening.

3. The article defined in claim 1 wherein the outside diameter of saidannular body is reduced adjacent said fluid outlet.

4. The article defined in claim 1 wherein said first flow directingvanes and said second flow directing partial vanes are of substantiallyrectangular cross-section.

5. The article defined in claim 1 wherein said second partial vanes areof increasing radial height over the portion of their length mostremoved from said fluid outlet so as to be tapered toward said fluidinlet.

6. The article defined in claim 1 wherein said first and said secondflow directing vanes are disposed from a line parallel with the axis ofsaid cylinder at an angular pitch of between about 45 degrees and about75 degrees.

7. The article defined in claim 1 wherein the angle of pitch of saidfirst flow directing vanes is gradually decreased to an angle of lessthan about 35 degrees adjacent said fluid inlet so as to afford saidvanes a more nearly axial orientation at said fluid inlet.

8. The article defined in claim 1 wherein said first and said secondflow directing vanes are uniformly spaced about the circumference ofsaid annular body member.

9. The article defined in claim 1 wherein four of said first flowdirecting vanes are uniformly spaced about the circumference of saidannular body member at 90 degree intervals and wherein four of saidsecond flow directing partial vanes are uniformly spaced about thecircumference of said annular body member at 90 degree interva s offset45 degrees from said first flow directing vanes.

10. The article defined in claim 1 wherein said annular body member hasa first exterior circumferential surface adjacent said fluid inletterminating at a radial face extending outwardly from said first surfaceand an adjacent circumferential surface of greater diameter than saidfirst surface and terminating at a second radial face extendingoutwardly from said second surface.

11. The article of claim 1 wherein said annular body member, said firstflow directing vanes and said second flow directing partial vanes are ofa unitary construction.

12. An end cone for a burner air tube, which comprises a hollowcylindrical member having a fluid inlet opening at one end and a fluidoutlet opening of reduced diameter at the opposite end, said cylindercomprising a right cylindrical section adjacent said fluid inlet havingan inside diameter substantially equal to said fluid inlet opening, anda concentric inturned cylindrical section adjacent said rightcylindrical section which defines an interior surface having a smoothtransition from the diameter of said right cylinder to that of saidoutlet opening, and wherein the outside diameter of said inturnedcylindrical section is reduced adjacent said fluid outlet; a pluralityof first flow directing vanes uniformly spaced about the circumferenceof said cylinder protruding from the interior surface of said cylinder,said vanes extending the length of said cylinder from said inlet openingto said outlet opening, said vanes being disposed from a line parallelwith the center axis of said cylinder at an angular pitch of betweenabout 45 degrees and about 75 degrees over a substantial portion oftheir length and wherein the angle of pitch of said vanes is graduallydecreased to an angle of less than about degrees adjacent said fluidinlet; and a plurality of second flow directing partial vanes protrudingfrom the interior surface of said hollow cylinder, said second vanesbeing alternately disposed between said first vanes and extending from apoint on the interior surface of said cylinder intermediate said ends tosaid fluid outlet, said second partial vanes increasing in height overthe portion of their length most removed from said fiuid outlet so as tobe tapered toward said fluid inlet.

13. The article defined in claim 12 wherein four of said first flowdirecting vanes are uniformly spaced about the circumference of saidhollow cylinder at 90 degree intervals and wherein four of said secondflow directing partial vanes are uniformly spaced about thecircumference of said hollow cylinder at 90 degree intervals offsetdegrees from said first flow directing vanes, said first and secondvanes having an angular pitch of about degrees and wherein said firstflow directing vanes are gradually curved to a pitch of about 25 degreesadjacent said inlet.

14. The article defined in claim 12 wherein said hollow cylinder has afirst exterior circumferential surface adjacent said fluid inletterminating at a radial face extend ing outwardly from said firstsurface and an adjacent circumferential section of greater diameter thansaid first surface and terminating at a second radial face extendingoutwardly from said second surface.

15. A burner of the type wherein an air tube is provided with a hollowcylindrical end cone having a fluid outlet of reduced diameter, an airshield concentrically disposed within said end cone so as to define anannular flow area between the outer periphery of said air shield and theinner surface of said end cone, and wherein said end cone is providedwith angularly disposed vanes on its interior surface to impartrotational motion to the fluids passing therethrough, the improvementwhich comprises: first vanes protruding from the interior surface ofsaid end cone and extending the length of said end cone, said vanesbeing disposed from a line parallel with the center axis of said endcone at an angular pitch "of between about 45 degrees and about degreesover a substantial portion of their length and wherein the angle ofpitch of said vanes is gradually decreased to an angle of less thanabout 35 degrees adjacent the inlet of said end cone; and

second vanes protruding from the interior surface of said end cone, saidsecond vanes being alternately disposed between said first vanessubstantially parallel therewith and extending less than the full lengthof said end cone terminating at said outlet end.

References Cited UNITED STATES PATENTS 2,066,651 1/1937 Sherman 239-4062,181,527 11/1939 Vollmer 239-406 2,265,904 12/1941 Herr. 2,657,74111/1953 Brierly 15876 X 2,796,923 6/1957 Fiske et a]. 15876 3,033,2785/1962 Soarr 158-1.5 X

M. HENSON WOOD, JR., Primary Examiner.

VAN C. WILKS, Assistant Examiner.

1. A BURNER END CONE COMPRISING AN ANNULAR BODY MEMBER HAVING A FLUIDINLET OPENING AT ONE END, A FLUID OUTLET OPENING OF REDUCED SIZE AT THEOPPOSITE END, AND AN INTERNAL FLOW PASSAGE EXTENDING THE LENGTH OF SAIDBODY MEMBER COMMUNICATING SAID INLET WITH SAID OUTLET; A PLURALITY OFFIRST FLOW DIRECTING VANES PROTRUDING FROM THE INTERIOR SURFACE OF SAIDBODY MEMBER INTO SAID FLOW PASSAGE AND EXTENDING THE LENGTH OF SAID BODYMEMBER FROM SAID INLET OPENING TO SAID OUTLET OPENINGS, SAID VANES BEINGANGULARLY DISPLACED FROM A LINE PARALLEL WITH THE CENTER AXIS OF SAIDBODY MEMBER; AND A PLURALITY OF SECOND FLOW DIRECTING PARTIAL VANESPROTRUDING FROM THE INTERIOR SURFACE OF SAID BODY MEMBER, SAID SECONDVANES BEING ALTERNATELY DISPOSED BETWEEN SAID FIRST VANES AND EXTENDINGFROM A POINT ON THE INTERIOR SURFACE OF SAID BODY MEMBER INTERMEDIATESAID ENDS TO SAID FLUID OUTLET.